Department of Environmental and Forest Biology, State University of New York College of Environmental Science and Forestry, One Forestry Drive, Syracuse, NY, 13210, USA.
Plant Reprod. 2014 Jun;27(2):69-78. doi: 10.1007/s00497-014-0241-3. Epub 2014 Mar 25.
MicroRNAs (miRNAs) are small RNAs that regulate genes involved in various aspects of plant development, but their presence and expression patterns in the male gametophytes of gymnosperms have not yet been established. Therefore, this study identified and compared the expression patterns of conserved miRNAs from two stages of the male gametophyte of loblolly pine (Pinus taeda), which are the mature (ungerminated) and germinated pollen. Microarray was used to identify conserved miRNAs that varied in expression between these two stages of the loblolly pine male gametophyte. Forty-seven conserved miRNAs showed significantly different expression levels between mature and germinated loblolly pine pollen. In particular, miRNAs representing 14 and 8 families were up- and down-regulated in germinated loblolly pine pollen, respectively. qRT-PCR was used to validate their expression patterns using representative miRNAs. Target genes and proteins were identified using psRNATarget program. Predicted targets of the 22 miRNA families belong mostly to classes of genes involved in defense/stress response, metabolism, regulation, and signaling. qRT-PCR was also used to validate the expression patterns of representative target genes. This study shows that conserved miRNAs are expressed in mature and germinated loblolly pine pollen. Many of these miRNAs are differentially expressed, which indicates that the two stages of the male gametophyte examined are regulated at the miRNA level. This study also expands our knowledge of the male gametophytes of seed plants by providing insights on some similarities and differences in the types and expression patterns of conserved miRNAs between loblolly pine with those of rice and Arabidopsis.
MicroRNAs (miRNAs) 是一类调节植物发育各个方面基因的小 RNA，但它们在裸子植物雄配子体中的存在和表达模式尚未确定。因此，本研究鉴定并比较了长叶松（Pinus taeda）雄配子体两个阶段（成熟（未萌发）和萌发花粉）的保守 miRNA 的表达模式。利用微阵列技术鉴定了这两个阶段的长叶松雄配子体中表达差异的保守 miRNA。47 个保守 miRNA 在成熟和萌发的长叶松花粉之间的表达水平存在显著差异。特别是，代表 14 和 8 个家族的 miRNA 在萌发的长叶松花粉中分别上调和下调。使用代表性 miRNA 通过 qRT-PCR 验证其表达模式。利用 psRNATarget 程序鉴定靶基因和蛋白质。22 个 miRNA 家族的预测靶基因主要属于参与防御/应激反应、代谢、调控和信号转导的基因类别。也使用 qRT-PCR 验证了代表性靶基因的表达模式。本研究表明，保守 miRNA 在成熟和萌发的长叶松花粉中表达。其中许多 miRNA 表达水平存在差异，这表明所研究的雄配子体的两个阶段在 miRNA 水平上受到调控。本研究还通过提供关于长叶松与水稻和拟南芥之间保守 miRNA 的类型和表达模式的一些相似性和差异的见解，扩展了我们对种子植物雄配子体的认识。
